Officials briefed on the interrogation say the 19-year-old suspect went silent after a magistrate judge and a representative from the U.S. Attorney's office gave him his Miranda warning. The officials insisted on anonymity because the briefing was private.

Before being advised of his rights, Tsarnaev told authorities that his 26-year-old brother, Tamerlan, recently had recruited him to be part of the attack that detonated pressure-cooker bombs at the marathon finish line, say two U.S. officials.

The CIA, however, had named Tamerlan to a terrorist database 18 months ago, say officials close to the investigation who spoke to The Associated Press on condition of anonymity because they are not authorized to discuss the case with reporters.